linux-kernel - [PATCH v2 4/8] VMCI: dma dg: set OS page size

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Date:   Thu,  3 Feb 2022 05:12:33 -0800
From:   Jorgen Hansen <jhansen@...are.com>
To:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Cc:     gregkh@...uxfoundation.org, pv-drivers@...are.com,
        Jorgen Hansen <jhansen@...are.com>,
        Vishnu Dasa <vdasa@...are.com>
Subject: [PATCH v2 4/8] VMCI: dma dg: set OS page size

Tell the device the page size used by the OS.

Reviewed-by: Vishnu Dasa <vdasa@...are.com>
Signed-off-by: Jorgen Hansen <jhansen@...are.com>
---
 drivers/misc/vmw_vmci/vmci_guest.c | 9 +++++++++
 include/linux/vmw_vmci_defs.h      | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/misc/vmw_vmci/vmci_guest.c b/drivers/misc/vmw_vmci/vmci_guest.c
index 5a99d8e27873..808680dc0820 100644
--- a/drivers/misc/vmw_vmci/vmci_guest.c
+++ b/drivers/misc/vmw_vmci/vmci_guest.c
@@ -581,6 +581,15 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
 	/* Let the host know which capabilities we intend to use. */
 	vmci_write_reg(vmci_dev, caps_in_use, VMCI_CAPS_ADDR);
 
+	if (caps_in_use & VMCI_CAPS_DMA_DATAGRAM) {
+		uint32_t page_shift;
+
+		/* Let the device know the size for pages passed down. */
+		vmci_write_reg(vmci_dev, PAGE_SHIFT, VMCI_GUEST_PAGE_SHIFT);
+		page_shift = vmci_read_reg(vmci_dev, VMCI_GUEST_PAGE_SHIFT);
+		dev_info(&pdev->dev, "Using page shift %d\n", page_shift);
+	}
+
 	/* Set up global device so that we can start sending datagrams */
 	spin_lock_irq(&vmci_dev_spinlock);
 	vmci_dev_g = vmci_dev;
diff --git a/include/linux/vmw_vmci_defs.h b/include/linux/vmw_vmci_defs.h
index 1ce2cffdc3ae..4167779469fd 100644
--- a/include/linux/vmw_vmci_defs.h
+++ b/include/linux/vmw_vmci_defs.h
@@ -21,6 +21,7 @@
 #define VMCI_CAPS_ADDR          0x18
 #define VMCI_RESULT_LOW_ADDR    0x1c
 #define VMCI_RESULT_HIGH_ADDR   0x20
+#define VMCI_GUEST_PAGE_SHIFT   0x34
 
 /* Max number of devices. */
 #define VMCI_MAX_DEVICES 1
-- 
2.25.1